In the drilling of oil and gas wells, a downhole drilling motor and a drill bit are attached to the end of a drill string. Most downhole drilling motors include a rotor rotating within a stator. The rotation of the rotor provides a vibration to the adjacent drill bit as it cuts through the subterranean formation to drill the wellbore. The drill string slides through the higher portions of the wellbore as the drill bit at the end of the drill string extends the wellbore deeper into the formation. A vibration tool is sometimes attached to the drill string a distance above the drill bit (e.g., 800-1,500 feet above the drill bit). The vibration tool provides vibration to the portions of the drill string above the vibration tool, thereby facilitating the movement of the drill string through the wellbore.
Conventional vibration tools include a power section made of a rotor rotating within a stator and a valve positioned below the rotor. As the rotor rotates, the valve periodically restricts fluid flow through the vibration tool, which creates a pressure pulse or waterhammer that is transmitted through the power section and up through the portion of the drill string above the vibration tool.